This invention relates generally to X-ray imaging apparatus and more particularly to an industrial X-ray inspection system capable of providing both film and high resolution fluoroscopic images of objects under inspection.
Industrial X-ray inspection systems are generally well known and are used for the non-destructive examination of objects such as castings, electronic components and assemblies as well as biological samples. Such apparatus include cabinets comprised of lead lined steel structures including a generally vertical tower assembly having an X-ray tube located at the top thereof. During an inspection procedure, a piece of X-ray film is normally placed on a shelf in the cabinet at the bottom of the tower and the object of interest is placed on top of the film. Such industrial X-ray systems also typically include means to adjust the voltage and exposure time to achieve optimum image contrast of the film image. The object is then exposed to X-rays which pass through the object to produce a shadowgraph on the X-ray film which becomes visible to the eye when developed. Such apparatus is similar in many respects to that utilized for medical procedures.
As in the case of medical X-ray examination systems, X-ray inspection systems used for industrial applications also utilize systems which provide fluoroscopic or "real time" imaging. These systems also employ X-ray tubes; however, instead of recording the X-ray image on film, the X-ray image is converted to a video image which is viewed via closed circuit television apparatus. In some such systems, a videcon tube converts the X-ray image directly into a video image which is displayed. Vidicon sensitive X-ray cameras, however, are expensive and short lived. In others, the X-ray image is converted to a visible image by a cesium iodide image intensifier for video viewing. Such apparatus is large and very expensive. One known type of image intensifier which has become extremely useful includes a thin coating of radioluminescent phosphor which is coupled to the input of a microchannel plate type image intensifier whose output is fed to a phosphor for generating a visible image which can thereafter be viewed. This type of apparatus is smaller in size and less costly than the above mentioned types.